// constants won't change. Used here to set a pin number:
const int ledPin = LED_BUILTIN;  // the number of the LED pin
const long interval1 = 1000;  // interval at which to blink (milliseconds)
const long interval2 = 100;  // interval at which to blink (milliseconds)


// Generally, you should use "unsigned long" for variables that hold time
// The value will quickly become too large for an int to store
unsigned long start1 = 0;  // 
unsigned long start2 = 0;

void setup() 
{
  pinMode(ledPin, OUTPUT);
}  

void TimeLed()   //led ze zije procesor
{
  unsigned long cas = millis();
  if (cas - start1 >= interval1)   //rozsviti led každou sec 
  {
    start1 = cas;
    digitalWrite(ledPin, HIGH);
  }
   if (cas - start1 >= interval2)   //zhasne led po 100 ms každou sec
  { 
    start2 = cas;
    digitalWrite(ledPin,LOW);
  }
}

void loop()
{
TimeLed();
}